Razor blade with rf sputtered coating

ABSTRACT

The specific disclosure provides for a razor blade comprising at least one cutting edge portion defined by two face portions having a narrow included angle therebetween. At least a portion of each of the face portions has an RF sputtered coating of a hard metal having a thickness of less than about 600 Angstrom units. The disclosure also provides for coating the sputtered metal coating with a sputtered coating of an organic plastic material having a thickness of from about 200 to about 2000 Angstrom units.

United States Patent 1191 111 3,7 54,329 Lane Aug. 28, 1973 [54] RAZOR BLADE WITH RF SPUTTERED 3,345,202 10/1967 Kiss 30/346,53 X COATING 3,480,483 11/1969 Wilkinson.... 30/341153 x 3,652,342 3/1972 Fischbein 30/346513 X [75] Inventor: George C. Lane, Danbury, Conn. [73] Assignee: Warner-Lambert Company, Morris Primary Examiner-0111B" Simpson Plains, NJ, Assistant Examiner-Gary L. Smith An .1 F. P J t 1. 22 Filed: Sept. 29, 1971 ames r e a [21] Appl. No.: 184,848 [57} ABSTRACT Related U.S. Application Data The specific disclosure provides for a razor blade com- [62] Division of Ser. No. 680,794, Nov. 6, 1967, Pat. No. prising at least one cutting edge Portion defined y two 153531 1 face portions having a narrow included angle therebetween. At least a portion of each of the face portions 52 us. (:1. 301346.53 has an RF sputtered coating of a hard metal h ing a 51 1111.0. B2611 21/54 thickness of less than about 600 Angstrom units- The 58] Field of Search 30/341553, 346 disclosure also pr s r ating the sputtered metal coating with a sputtered coating of an organic plastic 56] References Cited material having a thickness of from about 200 to about UNITED STATES PATENTS 2000 881mm 3,07l,858 1/1963 Alter 30/346513 12 Claims, N0 Drawings RAZOR BLADE WllTH RF SPUTTERED COATING CROSS-REFERENCE TO RELATED APPLlCATlON This patent application is a division of copending U. S. Pat. application Ser. No. 680,794, filed Nov. 6, 1967, now U. S. Pat. No. 3,635,811.

BACKGROUND OF THE INVENTION 1. Field of the Invention Generally, the present invention relates to a novel method and apparatus for surface coating of articles. More particularly, the field of the invention is that of metal substrate coating by a process analogous to metal transfer by so-called cathodic sputtering. In this process, the principal elements are an article or substrate to be coated, a coating material, a target plate for holding the coating material, electrode plates for causing gas plasma articles to strike the target to release the coating material, and means to control the deposition of the coating and means for carrying the article to be coated and for exposing the desired portions thereof to the sputtered coating.

The principal differences between the instant method and true cathodic sputtering are that the sputtered material need not be metallic, it is not a part of the cathode, and the process is of greatly improved efficiency in regard to rate and accuracy of deposition, operating temperature and in many other respects which are referred to further herein.

The method of the invention is desirably carried out by placing the electrode plates in a very high vacuum to form a peak or apex, with the upper edges thereof adjacent each other, and the lower edges more widely spaced apart and with an opening therebetween at the lower edges, placing the target plates immediately adjacent the inner surface of the electrode plates, impressing a very high frequency alternating current on the plates, causing electron flow therebetween and development of a high charge thereon, and leaking argon or like gas into the inter-electrode space. Thereupon, the electrons bombard the argon, ionizing it, and the plasma particles thus produced are attracted to the target plates by the space charge on the electrode plate. The plasma particles strike the target with such momentum that atoms or molecules from the target are sputtered from the target, whence, they are attracted to the article or substrate, which is suitably biased with regard to the electrode and target plates. Another aspect of the invention relates to the provisions of a mechanism for holding the desired articles or substrate, in this case, a plurality of razor blades, so that they may be passed in a controlled manner beneath the target plates containing the coating material. This mechanism may be generally described as a drum which is adapted to support a plurality of hubs which in turn support carrier means on which razor blades are removably mounted for coating. The drum and hubs are arranged, by means of an epicyclic gear or chain mechanism, so that they rotate in a desired timed relationabout two axes so as to expose the desired surfaces thereof to the opening beneath the target plates at particular angles to present those portions of the blade it is desired to coat to the target plates.

2. Description of the Prior Art In general, the prior art methods of coating particular substrates with various materials, particularly covering substrates with thin metallic films, has been accomplished by vacuum deposition of a thin film, generally by methods classified as evaporation, according to the following generally known methods.

A first method was an ordinary evaporation of a metal coating from a hot filament, wherein the filament was heated and the metal attached thereto was merely evaporated in the vacuum away from the filament along relatively straight lines in all directions, coating whatever object lay in their path. For example, in the art of electron microscopy, it is known to shadow a substrate by evaporating gold or other low boiling point metal onto a specimen in order to create solid phase or permanent shadows which would be easily visible under a microscope.

An improvement in the ordinary evaporation method was the so-called electron beam deposition whereby the coating material was held in one location and an electron beam was directed at the coating material, the beam being formed and maintained by the application of a magnetic field to an electron source. A heated filament was used in this method.

Another known method is so-called diode sputtering, wherein high energy electrons strike and ionize atoms of an inert gas as argon, and the ionized particles or plasma thus formed strike a target containing the coating. The target surface sputters off atoms which are attracted to an anode which contains the substrate. A method such as this is considerable improvement over several known methods, but the relatively large amount of ionized gas creates an arc effect and gives off considerable heat, even though this method has the advantages of somewhat greater uniformity and good adhesion of the coating material to the substrate. Another, more modern, method is so-called triode sputtering, wherein the substrate is rendered positive, and electrons from a hot cathode are directed at the target, following which coating atoms are sputtered to the substrate which was desired to be coated. Although this method of coating possesses a number of advantages, it is in some cases not commercially desirable for coating many types of substrates, especially such as razor blades; since although this method uses less argon than other methods, and a longer mean free path is made possible for improved efficiency, this method is best suited for transferring only metals and alloys thereof, and still relies for its source of energy on a hot wire cathode, which may introduce ionic contaminants of tungsten, for example. In addition, the coated surface requires finish grinding after plating.

All of the foregoing known methods of deposition of thin films have been considered and, although useful, they are not considered perfected for coating products having extremely fine cutting edges. Some of the purposes for which such coating is desired will now be discussed.

It has always been desired, in the razor blade art, to form a very sharp blade edge suitable for shaving, and to have that edge combine the advantages of corrosion resistance and longevity, as well as presenting a smooth and lubricious surface to the face of a shaver. Thus, it is desired to have a relatively corrosion-resistant blade having an extremely sharp surface and having the blade made from an extremely hard or tough material which would resist dulling. Thus, an ideal razor blade would combine the advantages of a long life in use as well as long shelf life, combined with an extremely sharp cutting edge and maximum smoothness for purposes of shaving comfort.

In the razor blade art, it is well known, in the interest of shaving comfort, "to coat a portion of the blade adjacent the cutting edge with a lubricious plastic, such as a fluorocarbon polymer, for example, polytetrafluoroethylene (Teflon) or a polymer such as polyethylene, or the like. Likewise, in the last several years, razor blades made from more corrosion resistant and tougher materials than those previously used have come into common use and have been accepted on a large scale commercially. Thus, the use of stainless steel for making razor blades is now quite common. However, it is likewise known that stainless steel is not the perfect material for making an ideal razor blade, but one which, at present, best combines the advantages of acceptable competitive cost, easy processability, corrosion resistance and durability of the shaving edge imparted thereto. However, even in spite of the great success of the stainless steel blade, there has been a demand in the razor blade art for a razor blade which would harmonize, at reasonable cost, the seemingly contradictory requirements of using a very hard, tough metal substrate for securing a long wearing blade edge, and using metals which, although sufficiently hard and tough to last for a long time, may nonetheless be readily ground to an extremely fine sharp edge, free from brittleness and microscopically jagged edges or voids in the sharpened surface.

Thus, a greatly improved razor blade would be' one in which the blade could be manufactured from conventional materials, such as ordinary steel or stainless steel, and could then be given a very fine smooth metal surface coating, which would not require further finishing of the coating metal to impart these characteristics to the edge. However, since no known materials combine these advantages, a great deal of effort has been placed on developing methods and apparatus for coating blade edges of existing type razor blades. However, metal coating already sharpened blade edges by conventional methods has always resulted in an edge which requires further finishing, and the application of a hard coating, such as chromium, has resulted in a blade which was very brittle near the edge portions, and which was very difficult to grind down or polish to the desired degree of smoothness, especially at a reasonable cost.

Thus, there has been a great demand for a simple and economical method of placing a fine, hard, extremely smooth coating on a finished razor blade edge portion which would not require further treatment, but which would impart to such a blade edge the desirable characteristics of smoothness and hardness as well as corrosion resistance.

The invention of the applicant, namely, the method of coating the blade edge by means of radio frequencyinduced plasma sputtering, and the development of an apparatus for carrying out this method, accomplished its objects, namely, the provision of a method and apparatus for improved surface coating of razor blades and like substrates.

SUMMARY OF THE lNVENTlON In view of the shortcomings of prior art methods and apparatus for coating razor blades, it is an object of the invention to provide an improved method and apparatus for placing a very then, very fine coating, either organic or inorganic, on a sharpened metal surface after sharpening such a surface, to provide an improved blade or the like.

A further object of the present invention is to provide a method of coating a desired substrate with a desired coating material at low temperatures and at a reasonable cost, and to attain an extremely uniform coating which needs no further treatment to present a sharp cutting edge to the user.

Another object is to provide an apparatus for carrying out radio frequency-induced plasma sputtering of a metal, metal oxide or other metal compounds or nonmetal coating material onto a razor blade.

Still another object of the invention is to provide a coating apparatus which is simple and compact to facilitate ready inclusion and use thereof in a high vacuum chamber.

Another object is to produce a razor blade or like article with a sharp cutting edge which is suitable, after being treated as described herein, to be further processed as by coating with a polymer, without the need for additional intermediate preparation steps.

By sputtering," as used herein, is meant the slow disintegration of a target under the bombardment of ionized gas molecules, and, more particularly, the disintegration of a coating material which is placed on the target and transferred to a substrate after being sputtered from the target. The coating material is moved from the target plates to the substrate by a so-called RF induced plasma sputtering process.

The present invention achieves its objects and overcomes the disadvantages of the prior art by providing a method which includes the steps of providing a sputtering module which includes two flat electrode plates arranged to form a peak at one end thereof and an opening opposite the peak, placing target plates containing the coating material in front of the electrode plates, providing carrier means for supporting a plurality of articles to be coated, drawing a very high vacuum in the area surrounding the sputtering module and the carrier means, impressing a radio frequency current across the electrode plates and electronically biasing the carrier means with respect to the electrode plates, leaking an inert gas into the region between the plates and passing the articles to be coated across the opening between the peaked plates so that electron bombardment of the gas ionizes the gas, the ions strike the target plates, sputtering the surface material therefrom, and the articles are uniformly coated by the sputtered material.

The method is advantageously performed by an apparatus which includes a drum or like means for carrying a plurality of articles holders past the sputtering module, and exposing a desired portion of the blades or other articles held on the carrier to the opening in the sputtering module in a timed relation so as to obtain a coating of desired uniformity, thickness and adhesion to the article. A preferred embodiment includes a drum holding a plurality of rotating hubs, and an epicyclic drive mechanism for rotating each of the articles carriers into a desired location as each hub unit passes the sputtering module, by utilizing relative rotation of the drum and hub assemblies.

In one embodiment, a metal coating is sputtered onto the edge portions of razor blades, and in other embodiments, organic polymers or other high-molecular weight coatings are transferred to a substrate, in some cases with simultaneous partial chemical breakdown, rearrangement, or other chemical or physical reaction during the sputtering process, and in still further embodiments, metal oxides, alloys, or other metal compounds are transferred, or simultaneously formed and transferred.

Other and further objects and advantages of the present invention, including the manner of attainment thereof, will become more apparent when considered in conjunction with a description of the preferred embodiments of the invention described further herein.

In keeping with the teachings of the present invention, a number of different products were made according to the processes set forth in detail below.

EXAMPLE 1 The apparatus shown in FIGS. 1 to 4 ofU. S. Pat. No. 3,635,81 1 was used with a bell jar comprising the outer vacuum chamber. U. S. Pat. No. 3,635,811 is incorporated herein by reference. A plurality of razor blades were carefully cleaned, as by immersing them in, and evaporating therefrom, a solvent, such a trichloroethylene or other suitable solvent. The blades were placed on holding means, such as a bayonet unit shown.

A pair of target plates were prepared by taking two mild steel plates, placing a heavy chromium plating on one surface of each plate by a conventional electrolytic deposition method. The plating may be of any desired thickness. Thereafter, these plates were secured to the inside surfaces, respectively, of the electrode plates.

Thereafter, a mechanical roughing pump was turned on, evacuating most of the air from the vacuum chamber to a pressure of 100 microns approximately. By means of an oil diffusion pump and cold trap, the pressure inside the air chamber was further evacuated until a pressure of l X millimeters of mercury was attained.

Thereafter, by means of a needle valve or like socalled leak valve argon gas was allowed to be introduced into the chamber until pressure was raised to 3 X 10 millimeters of mercury(Torr).

Thereupon, the radio frequency generating unit such as that shown in FIG. 6 of U. S. Pat. No. 3,635,811 was actuated, and a radio frequency of 13.56 megacycles per second was impressed on the plates, the matching network assocaited with the RF unit being adjusted or tuned so as to minimize the impedance mismatch caused by the lead of target plates. Charging of the plates with the R. F. current immediately causes a plasma to produced between the plates. Thus, the electrons emmited by the plates rush back and forth therebetween at a frequency of about thirteen million complete back and forth cycles per second and many of these electrons strike the atoms of argon gas disposed between the plates. Because of the argon atoms or other inert gas atoms, are very massive in relation to the mass of electrons, the argon atoms or molecules themselves are not substantially moved by the movement of the electrons or attracted by the charge which builds up on or closely surrounding the plates. However, the high frequency electrons bombarding the argon gas cause ionization thereof, and upon ionization each positive ion of argon is strongly attracted, by reason of the high negative charge, to one or the other of the plates. This high space charge accelerates the argon atoms toward the electrode with great energy. However, the ionized atoms strike the target material which is placed on the target plate placed immediately in front of the electrode. The momentum with which the ionized argon atom strikes the target plate may be sufficient to sputter one or more atoms or molecules off the target plate.

When initial ionization takes place, the pressure is reduced by reducing the rate of addition of argon, to approximately 1.5 X 10' mm of mercury. Thereupon, the RF energy input is raised to a value of 600 watts forward power.

A DC bias of 1800 volts is built up between the RF system and the blade or article carrying means, this bias resulting from the negative space charge on the plates in relation to the potential of the carriers, which are fully insulated from the plates. The bias occurs because of the intrinsic characteristics of the circuit, that is, the plates take on, or appear to take on, a strong negative charge. While the particles which are sputtered from the target plate are in a neutral state, that is, they are not ionized, and therefore are not attracted to the substrate or article to be coated by reason of the bias between the plates and the article carrier, a certain degree of bias is desirable to prevent positively charged argon or like ions from striking the articles, since this would result in resputtering either the substrate or the coating sought to be applied.

Thus, the bias between the plates and the carrier is desirable, but its value is not of critical importance to the invention.

Thereafter, the amount of forward power in the system is then adjusted by altering the amount of argon introduced into the system by a very minute adjustment. It is preferred that after arriving at a pressure of between 1 and 2 X 10" millimeters, and adjusting the impedance matching network, there will be about 500 to 600 watts forward power and about watts or less of reflected power, leaving a net power input into the plasma peak or to the two plates and the area therebetween of about 500 to 600 watts, and preferrably about 510 to 550 watts. Power levels of greater or lesser quanity will directly affect sputtering rate. Under these conditions, sputtering will proceed for a period of approximately four minutes, and a coating having a thickness of about 625 Angstroms (A.) will be deposited upon a flat surface, and half that thickness, namely 264 Angstroms, will be deposited on the edge portions of a razor blade, disposed with the razor edge portion thereof directed generally to the area between the plasma peak.

The razor blades coated by the process just set forth were shown to process an extremely fine, pore-free and uniform coating of chromium, rendering them resistant to rust and corrosion. Such blades, which possessed a very sharp or keen edge, also required no further honing or other treatment, and were ready for next process stage when removed from the vacuum chamber.

Although the exact reasons for the success of the sputtering apparatus and method of the present invention, are not entirely understood, it is believed that, because the coating material is liberated from the target plate in substantially atomic or molecular size particles, the adhesion thereof to the substrate or articles to be coated is not only very strong but, since the charges possessed by the coating material particles are the same and such charges tend to repel each other, the individual atoms each tend to seek out one particular location in the substrate and repel other atoms from that immediate area until the entire substrate is uniformly covered and thus attains a fine, even coating surface.

By charges, as used in the preceding paragraph, referring to the charges on the particles of the coating material, it will be understood that these particles are not ionized, but merely have a slight electrostatic or like surface charge of an extremely small magnitude.

In fact, if a physical analogy might be made, the sputtered atoms or molecules act, upon contacting the substrate or article to be coated, somewhat as droplets of water when placed or spilled on hot frying pan or the like. Thus, in this analogy, the droplets of water would be compared to atoms having a surface charge, and the fine subdivision and rapid movement thereof is characteristic of the atoms striking the substrate. Thus, the atoms being surrounded by their own charge, much as the heated droplets of water are surrounded by a vapor phase of their own, tend not to coalesce in one location but to spread themselves about in a random manner. Thus, a razor blade like article coated according to the present invention is characterized by an extremely thin but very smooth coating, since the method apparently creates a coating in which the deposited or coating material is placed upon the substrate substantially literally one molecule at a time.

EXAMPLE 2 It is also well known, in the razor blade art to coat a portion of a razor blade in an area which is very close to the cutting edge with a polymer having lubricious characteristics, such as a polytetrafluoroethylene or like fluorine-or chlorine-containing polymers, or polyethylene, or other lubricious plastic material. However, prior methods have involved suspending the polymer in a solvent or the like and, after placing a liquid phase coating on the blade, evaporating the solvent and curing the polymer. However, as set forth below, the present method may be used for direct polymer coating of blades or the like. Initially, steel plates or blades approximately 6 inches by 9 inches in size and about one fourth of an inch in thickness where sprayed with a film of polytetrafluoroethylene and the coating thus sprayed was baked out or cured in a reducing atmosphere for 20 minutes at 700 degrees F.

It is preferred to perform this operation in a very high vacuum to avoid entrapping gases in the coating which could create a reaction with the polymer or other materials present in the chamber or interfere with the generation of the plasma.

These plates were clipped into position just inside and adjacent the plates into the position shown in FIG. 1 of U. S. Pat. No. 3,635,811.

Next, razor blades were cleaned as set forth above, in Example 1, by immersing in a solvent or the like.

Next, the bell jar was evacuated by means of mechanical and diffusion pumps to a pressure of l X 10 millimeters of mercury. Thereupon, argon was introduced until the pressure attained a level of 3 X 10 millimeters of mercury, and a plasma was achieved at this pressure by impressing approximately 100 watts of R.F. energy across or into the peak defined by the plates. Once ionization took place, that is, once the plasma was established, the argon pressure was reduced to an operating level of 1.5 X 10* millimeters of mercury.

Thereupon, the RF. energy was increased to a net power of about 275 watts, that is, about 300 watts forward power and 25 watts reflected power. In this example, the bias between the grounded carrier unit and the plates was approximately 800 volts of self-biased DC. In this example, the process was continued for a period of approximately 5 minutes. Under these conditions, approximately I200 A. of a plastic material were deposited on an optical flat which was placed in the chamber near the articles to be coated, and the coated articles contained a corresponding amount of plastic material, depending on their configuration that is, on the amount of surface and angle thereof presented to the plates. A coating such as this may be deposited in any desired thickness, preferably, in this case about 200 to 2000 A. in thickness.

Analysis of the films deposited by this method, by both intra red spectroscopy and nuclear magnetic resonance (NMR), showed that the deposited plastic was of different composition than that of the plastic which was placed on the plates, differing in that some of the characteristic CF (Carbon-fluorine) bands had disappeared, and in that the molecular weight of the coating material, had been reduced by an order of some of two to five times. The resulting polymer deposited on the substrate or coated article was nevertheless a somewhat similar polymer, containing the same elements even though the exact crystal structure of the initial polymer has been considerably altered. Thus, this example demonstrates the use of the novel method for simultaneously depositing and altering or rearranging a polymer in one step.

EXAMPLE 3 In this example, all the conditions were the same as those set forth in Example I; the coated material was chromium, a plurality of blades were placed on the bayonet or carrying unit, and a plurality of these carrier units were inserted into the hubs. Thereafter, the sputtering process was carried out in accordance with the conditions of Example 1, except that it was continued for a longer time, and the entire carrier unit was revolved through two complete cycles, thus exposing the top and bottom edges of the plurality of razor blades held in each bayonet unit to the plasma peak or sputtering module for the same length of time and at the same angle as all the other blades. The process was timed so that a coating of approximately 200 to 300 A. of chromium was deposited on the edge portion of each razor blade. In this example, the argon was continually admitted during the process, maintaining the operating pressure set forth in the first example and the sputtering took place continuously until each bayonet unit had made two passes beneath the sputtering module. The drum unit was revolved at a rate of one quarter of a revolution per minute and two complete cycles of rotation thus coated both edges of all baldes in eight minutes of operation. The coating thickness referred to herein and in Example 1 are merely illustrative, since these coatings may be of any desired thickness.

EXAMPLE 4 In this case, a process similar to that set forth in Example l was carried out, except that the deposited material, instead of being metallic chromium, was an alloy iron, nickel and chromium, one brand of which is known as Nichrome. After carrying out the process according to the conditions set forth in Example I, it was discovered that the article, contained a coating of the alloy which was placed on the target plates in the same exact composition as the composition of the alloy on the plate. Thus, the method demonstarated its ability to transfer an alloy from the target to the substrate without altering the composition of the alloy.

EXAMPLE In this example, the conditions were the same as those set forth in Example 3, except that the coating material was the alloy of Example 4.

EXAMPLE 6 In this example, conditions were the same as those in Example 1 or 4, except an iron carbide material, having a very hard surface, was coated onto a razor blade by the same process.

EXAMPLE 7 A method such as that referred to in Example 1 was carried out, with all conditions thereof remaining the same, except that during the time the argon was leaked into the bell jar, a small amount of oxygen was allowed to enter the jar. By allowing sufficient oxygen to enter the jar to react with the chromium, but not enough oxygen so as to substantially diminish the vacuum in the system or to interfere with the creation of the plasma, it was discovered that a coating of chromium oxide was able to be placed on the blades. Thus, this method demonstrates the ability of the method of the present invention simultaneously to carry out coating deposition and to allow a chemical reaction between the coating material and another product introduced into the vacuum chamber.

It is believed that, since the sputtered coating material is generally in a monoatomic or monomolecular form, the availability of individual atoms or molecules for reaction is great, and the probabilities of the desired reaction taking place are excellent. Thus, a principal advantage of this method is that it makes possible what is essentially a gas phase reaction at temperatures greatly below the vaporizing or sublimation temperatures of refractory materials, such as, for example, the types of metals referred to herein.

Those blades referred to in the preceding examples in which a metal or metal-containing compound was applied to the edge were suited to receive an additional coating of plastic, over the newly coated edge, either by a subsequent sputtering operation or by conventional methods.

As pointed out above, a principal advantage of this method is that no treatment subsequent to sputtering is required to prepare the coated article for use or for a subsequent coating operation. Particularly in the case of razor blades, this is a great advantage, since, in the past, two honing operations were required for a blade with a coated edge, and honing is an operation which adds considerably to the cost of a blade.

The above described method makes possible the application of films, whether metallic, inorganic, or organic, of thickness which are thinner than those previously achieved in the cutting edge and razor blade art, for example.

As set forth in Example 1, a razor blade prepared according to the present invention will have a coating, for example, of a thickness of 100 to 600 Angstroms, that is, between one and six one-hundredths of a micron. Thus, although it has been known to apply metal coatings, for example, by evaporation, in thickness of somewhat less than a micron, it is believed that it is not heretofore known to coat a blade with a thickness of metal of one to six one-hundredths of a micron.

It is believed that one reason that such a thin coating is satisfactory is that the sputtered molecules have such momentum, when sputtered from the target, that they are firmly held by the substrate, and, in addition, since no subsequent honing or stropping is required it is not necessary to add additional thicknesses of material, which would then merely be grounded away in a resharpening operations.

Likewise, coating the fluorocarbon, hydrocarbon, or other polymer over an ordinary carbon steel blade edge, over a stainless steel blade edge, or even over an edge coated with chromium according to the method of the present invention, or otherwise, is believed novel in that such coating may be applied with a thickness of as little as 200 Angstroms or less, or as large as 1200 to 2000 Angstroms or more. Such coating thicknesses are much smaller than those presently able to be achieved by other methods. In addition, blades having such thin coatings have not been heretofore known, since it has not been possible to apply such a thin coating in a reproductible manner.

Although the reason therefor is not clearly under stood, it is known that coatings such as those described herein may be applied to the cutting edges of blades, as described, without joining the edges together. It is possible that, since the electrode plates are disposed at an angle relative to the faces which define the cutting edges of the blades or other instruments, that sputtered molecules do not ordinarily have a vertical trajectory, and thus do not tend to fly vertically into the valleys between blade edges, at least in substantial numbers compared to the number striking the faces near the cutting edges. At any rate, there has somewhat unexpectedly been no problem with blades sticking together; this is another advantage of the invention which facilitates treatment of large numbers of blades at low cost.

it will thus be seen that the present invention provides a novel apparatus, method and articles having novel advantages and characteristics, including those hereinbefore pointed out and others which are inherent in the invention.

Having completed a disclosure of my invention, in keeping with the patent statutes, so that one skilled in the art may practice the invention, 1 contemplate that certain variations may be made herein without departing from the spirit of the invention or the scope of the appended claims.

What is claimed is:

l. A razor blade including at least one cutting edge portion defined by two face portions having a narrow included angle therebetween, said razor blade having a radio frequency induced plasma sputtered metal containing coating on at least a portion of each of said face portions, said coating having a thickness of less than about 600 Angstrom units.

2. A razor blade as defined in claim 1 in which said coating comprises a metal alloy having a thickness of from about to about 600 Angstrom units.

3. A razor blade as defined in claim 2 in which said alloy is an alloy of nickel, iron and chromium.

4. A razor blade as defined in claim 1 in which said coating is an iron and carbon compound.

metal is chromium.

10. A razor blade as defined in claim 1 in which said coating is a metallic oxide.

11. A razor blade as defined in claim 10 in which said metallic oxide is chromium oxide.

12. A razor blade as defined in claim 7 wherein said sputtered hard metal coating has thereon a sputtered coating of an organic plastic material having a thickness of from about 200 to about 2000 Angstrom units. 

2. A razor blade as defined in claim 1 in which said coating comprises a metal alloy having a thickness of from about 100 to about 600 Angstrom units.
 3. A razor blade as defined in claim 2 in which said alloy is an alloy of nickel, iron and chromium.
 4. A razor blade as defined in claim 1 in which said coating is an iron and carbon compound.
 5. A razor blade as defined in claim 1 in which said coating consists of chromium.
 6. A razor blade as defined in claim 5 in which said thickness is between about 100 and about 600 Angstrom units.
 7. A razor blade as defined in claim 1 in which said coating is a hard metal.
 8. A razor blade as defined in claim 7 in which said thickness is between about 100 and about 600 Angstrom units.
 9. A razor blade as defined in claim 7 in which said metal is chromium.
 10. A razor blade as defined in claim 1 in which said coating is a metallic oxide.
 11. A razor blade as defined in claim 10 in which said metallic oxide is chromium oxide.
 12. A razor blade as defined in claim 7 wherein said sputtered hard metal coating has thereon a sputtered coating of an organic plastic material having a thickness of from about 200 to about 2000 Angstrom units. 